-Food web structure can be partly characterized by species' trophic level - In marine fish, trophic level appears positively correlated to individual body size at the community scale (Jennings et al 2001) -Trophic level may change across sizes but also taxa, seasons, and habitats -Very few studies have addressed how size-dependence of trophic position varies in space, i.e. according to habitat, and whether observed community-scale patterns hold at the level of species or guilds.